1. Field of the Invention
The present invention relates to a semiconductor processing machine with a modified structure, and more particularly to a wafer ion-implanting machine with a modified structure.
2. Description of Related Art
In the course of ion implantation, in order to successfully allow the ions to be implanted to enter a wafer at various incident angles, the wafer ion-implanting machine must be equipped with a moving module responsible for moving the wafer up and down so that the ions may be implanted at corresponding incident angles. Referring to FIG. 1 and FIG. 2, the conventional moving module of the wafer ion-implanting machine includes a wafer carrier 1a, a moving shaft 2a, a base 3a, a pair of air cushions 4a, and a fixture body 5a. A wafer tray 11a is further pivotally connected to a top of the wafer carrier 1a, while a bottom of the wafer carrier 1a is fixed onto a top of the wafer tray 2a. The moving shaft 2a can move lengthwise and therefore drive the wafer carrier 1a and the base 3a to move lengthwise. The fixture body 5a is located between the pair of air cushions 4a. Each of the cushions 4a has a plurality of tiny holes 41a to which air is input through a pipe 6a. The input air strikes at opposite sides of the fixture body 5a from the holes 41a. The base 3a can be driven by the moving shaft 2a to stably move lengthwise, provided that the air pressure on the opposite sides of the fixture body 5a remains balanced. In order words, for a traditional wafer ion-implanting machine, only when the air cushions 4a is kept away from contact with the fixture body 5a can the frictional force that is generated by physically contacts between the fixture body 5a and the air cushions 4a be prevented from occurring; furthermore, once the frictional force occurs, then the moving shaft 2a is prevented from going up and down freely without any rotation, which would cause the wafer carrier 1a to be tilted and further affect the incident angles of implanting ions.
In practice, it is not easy to implement the balance of the air pressure so as to prevent the occurrence of frictional force between the air cushions 4a and the fixture body 5a. Long-term friction would significantly damage the air cushions 4a and the fixture body 5a, causing an increase in maintenance cost. Furthermore, friction between the air cushions 4a and the fixture body 5a causes the wafer carrier 1a to become tilted when the wafer carrier 1a moves up and down. Unsteady movement of the wafer carrier 1a disadvantageously influences the incident angle of implanting ions and therefore reduces the wafer yield.